二维苯并咪唑醋酸锌MOF功能化聚丙烯腈复合隔膜用于实现无枝晶锂金属电池

2D Zn(Bim)OAc MOF functionalized polyacrylonitrile composite separator for Lit redistribution to achieve dendrite-free lithium metal batteries

锂沉积/剥离过程中的枝晶形成生长和库仑效率降低导致电池循环寿命缩短,限制了锂金属电池(LMBs)的商业应用。通过静电纺丝结合真空过滤技术成功制备了具有调节Li+通量和提高Li^(+)迁移数(tLi^(+))的二维苯并咪唑醋酸锌MOF功能化聚丙烯腈(Zn(Bim)OAc-PAN)复合隔膜,Zn(Bim)OAc纳米片的引入固定了阴离子,提高了离子电导率(2.13 mS/cm)和Li^(+)迁移数(0.67)。同时,Zn(Bim)OAc纳米片上的孔隙和纳米片之间堆叠形成的纳米流体通道协同构筑了微纳孔道结构,降低了复合隔膜的孔径,使通过隔膜的Li+流分布均一,促进Li^(+)在锂金属表面均匀沉积。因此,Zn(Bim)OAc-PAN隔膜组装的Li|LiFePO_(4)电池表现出了更高的初始容量(146.6 mA·h/g)和更好的循环稳定性(300次循环后容量保留率为96.3%)。此外,Zn(Bim)OAc-PAN复合隔膜组装的Li|Li电池实现了在1 mA/cm^(2)下长达1000 h的稳定循环,循环后的锂金属表面没有明显的锂枝晶生长。本文为通过隔膜调节Li+通量来提高锂金属电池性能提供了一种可行的策略。

The dendrite formation and growth during Li plating/stripping process,as well as the reduced coulomb efficiency,result in a shortened cycle life of lithium metal batterie(LMB),restricting its commercial application.2D Zn(Bim)OAc MOF functionalized polyacrylonitrile(Zn(Bim)OAc-PAN)composite separator with regulating Li^(+)flux and increasing Li^(+)migration number was successfully prepared by electrospinning combined with vacuum filtra-tion technology.The introduction of Zn(Bim)OAc nanosheets can fix the anion,improve the ionic conductivity(2.13 mS/cm)and Lit migration number(0.67).Meanwhile,the pores on Zn(Bim)OAc nanosheets and the nano-fluid channels between the stacked nanosheets synergistically construct a micro/nano pore structure,reducing the pore size,resulting in uniform Li^(+)flux distribution and promoting uniform Li^(+)deposition on the lithium metal surface.Therefore,as-prepared Zn(Bim)OAc-PAN separator assembled Li|LiFePO_(4)cells can also exhibit higher initial capacity(146.6 mA·h/g)and better cycle stability(96.3%capacity retention after 300 cycles)at 2 C.Besides,as-prepared Zn(Bim)OAc-PAN separator based LijLi achieves a stable cycle up to 1 ooo h under 1 mA/cm^(2),and there was no obvious lithium dendrite growth on the Li anode surface after cycling.The reported approach provides a feasible strategy to improve the LMB performance by regulating the Li*flux through separators.